Digital phase-shift modulation for an isolation buffer in silicon-on-sapphire CMOS

We designed and fabricated a 4-channels digital isolation amplifier in a 0.5 mu m Silicon-on-Sapphire technology. The isolation device was fabricated on a single die, taking advantage of the isolative properties of the sapphire substrate. The individual isolation channels can operate in excess of 40Mbps using digital phase-shift-keying modulation. Modulation of the input signal is used to increase immunity to errors at low input data rates. The device can tolerate ground bounces of 1V/mu s and isolate more than 800V. The device uses N+1 capacitors for N channels as opposed to 2N of previous implementations, thus minimizing the coupling silicon area and increasing reliability. Typical applications are in harsh industrial environments, transportation, medical and life-critical systems.